Transport of dietary cholesterol into blood and milk of the goat.

Position 4 labeled carbon-14 cholesterol was placed in abomasums (stomachs) of two lactating goats. Blood and milk samples were collected from the animals for 5 to 13 days. Specific activities of cholesterol and cholesteryl esters in various fractions of blood serum and milk were determined to reveal pathways by which dietary cholesterol enters milk. Results with the two animals showed similar trends. Within 24 h both cholesterol and cholesteryl esters of the three principal serum lipoproteins of the goat were labeled, and this labeling persisted in substantial degree for the 13-day experiment. Specific acities for cholesteryl esters in milk fat globules exhibited several remarkable attributes: they fluctuated in intensity with a 3-to 4-day cycle reaching a maximum at 7 to 8 days after tracer injection; they exceeded cholesteryl ester specific activity in the skim milk by an order of magnitude; and at their maximum they exceeded all specific activities for serum components. The results of this investigation exemplify the ease with which dietary cholesterol enters and crosses membranes in the animal body.     

Polyelectrolytes

Summary The polymerization of N,N-dimethyl-3,4-dimethylene-pyrrolidinium bromide was carried both in the presence and absence of initiators. Aqueous solutions with 10–50% monomer were polymerized by heating at 60°. The conversion time decreased with increased monomer concentration and molecular weight increased with increased monomer concentration. High monomer concentration also yielded significant amounts of monomer dimer.     

The importance of sputum cytology in the diagnosis of lung cancer: a cost-effectiveness analysis

STUDY OBJECTIVE: To assess the potential health and cost effects of initial testing with sputum cytology to diagnose lung cancer. DESIGN: Cost-effectiveness analysis. DATA SOURCES: Surveillance Epidemiology and End Results (SEER) program; cost data from Northern California Kaiser Permanente Hospitals and Universities of Stanford and Iowa; National Center for Health Statistics; and a MEDLINE search. INTERVENTIONS: The use of sputum cytologies preceding other tests (ie, fine-needle aspiration, bronchoscopy, thoracoscopy) in patients with suspected lung cancer. MAIN OUTCOME MEASURES: Mortality associated with testing and initial surgical treatment (eg, performance of thoracoscopy to remove a local-stage, centrally located cancer), cost of testing and initial treatment, life expectancy, lifetime cost of medical care, and cost-effectiveness. RESULTS: In central lesions, sputum cytology as the first test was the dominant strategy because it both lowers medical-care costs ($2,516 per patient) and lowers the mortality risk (19 deaths in 100,000 patients) of the evaluation without adversely affecting long-term survival. In peripheral lesions, sputum cytology costs less then $25,000 per year of life saved if the pretest probability of cancer exceeds 50%. The estimated annual savings of adopting sputum cytology as the first test for diagnosing lung cancer in the United States is at least $30 million. CONCLUSIONS: Experience in regional centers indicates that sputum cytologic testing is infrequently ordered before implementing invasive diagnostic techniques, even in patients with central lung masses. The study findings suggest that sputum cytology as the first test in suspected lung cancer is likely to be cost saving without adversely affecting patient outcomes.     

The utility of parotid gland and level I and II neck fine-needle aspiration

OBJECTIVE: Although fine-needle aspiration (FNA) commonly is used in the diagnostic workup of parotid gland and level I and II neck lesions, the effect of an FNA service on patient care has not been definitively established. METHODS: Follow-up was obtained in 158 patients who underwent FNA. The value of FNA was analyzed by determining the proportions of cases in which management was altered by the information obtained. RESULT: The percentage of lesions classified by FNA as benign, nonneoplastic; benign, neoplastic; atypical or suspicious; malignant; and insufficient was 42%, 28%, 16%, 41%, and 7%, respectively. By using FNA, an operation was avoided in 70% and 79% of patients with a nonneoplastic lesion and a metastasis, respectively. CONCLUSIONS: Although definitive subclassification of some lesion types was poor, FNA was useful in patient triage.     

The mechanism of photochemotherapy

As a contribution to the mechanisms of photochemotherapy, human skin homogenates were irradiated in the presence or absence of methoxsalen. The changes induced in LDH-, G-6-PDH-, GAPDH-, and GOT-activities were registered. Methoxsalen (50 mug/ml) failed to produce any significant effect. On pure G-6-PDH, methoxsalen exhibited a photoprotective action.     

Derivatives of eigenvalues and eigenvectors of a general complex matrix

A survey of methods for sensitivity analysis of the algebraic eigenvalue problem for non-Hermitian matrices is presented. In addition, a modification of one method based on a better normalizing condition is proposed. Methods are classified as Direct or Adjoint and are evaluated for efficiency. Operation counts are presented in terms of matrix size, number of design variables and number of eigenvalues and eigenvectors of interest. The effect of the sparsity of the matrix and its derivatives is also considered, and typical solution times are given. General guidelines are established for the selection of the most efficient method.     

The Impact of Air Pollution on a Regional Economy

A study was made to determine a more comprehensive method of estimating the impact of an air pollutant on a region's economy. To do this, a Leontief input-output model of Clinton County, Pennsylvania was employed. Economic and related changes were simulated with the model by making appropriate changes and/or additions to the parameters of the model, i.e., the technical coefficients and elements of the external income input vector. In this specific application, the technical coefficients were represented by Direct Cost Response Functions in which the technical coefficient was a function of pollutant concentration. These functions were derived for the coefficients of all sectors whose expenditure pattern was affected by the pollutant. With these functions, it was possible to modify the base model to reflect the effect of different levels of pollutant concentration in the region. Economic impact studies yielding the direct and indirect changes in expenditures in all sectors of the model were then carried out showing the cost of air pollution damages to the region.